Sending Apple Watch specific content

There are two main content types used in all HTML emails: text/plain and text/html MIME types.

You should always include a plain text version of your email that closely matches to the HTML version of your email. Mail.dll will generate (extract) plain text automatically, if you provide HTML text only.

Usually Apple watch displays only the plain text part of your email. In most cases it considers the HTML too complicated (e.g. external images are referenced), so it shows the plain text version instead.

External image is an image that isn’t embedded in the email, using cid: protocol, but loaded from a remote HTTP server using a standard <img src=’…’ /> tag.

You can use ‘text/watch-html’ type to send a limited HTML version of your message to Apple Watch users, resulting in rich text-like messages on Apple Watch devices.